“...They look home-made”
They are not.
The top (with the cylinder on the muzzle) is the MK II variant of Britain’s STEn submachine gun of WWII.
The second is a CZ25, one of the earliest submachine guns to use a recessed bolt. Design fundamentals have been widely copied and some credit the CZ25 with having a major influence on the design of the Uzi.
The STEn went out of production in the 1940s and the CZ25 was discontinued in 1968. It’s anybody’s guess how they arrived on US territory.
Full auto guns have been highly regulated in the US since 1934, and it’s highly illegal for private citizens to own unregistered items. But such guns can be found regardless; ought to suggest to the average person the futility of gun bans.
I believe the bottom submachine gun is a vz.26 (a vz.25 with a folding stock) It is chambered in the 7.62x25 round. You can see some 7.62x25 ammo in the picture and magazines.
I think the revolver is a Rohm RG-10 (.22 rimfire), but hard to be certain.
I am pretty sure the singleshot pistol is not a flare gun but a Cobray .45/.410 derringer. They were available in kit form.
I suspect the Cobray and the two sub-machine guns were constructed from kits, essentially homemade on the black market. The homeless man is a convicted felon, so it would make sense for him to have black market guns.
I doubt that the two sub-guns and the Cobray derringer have any serial numbers.